1. Field of the Invention:
The present invention relates to novel organotin fluorides, and, more especially, to novel dialkyltin fluorides having controlled morphology and to a process for the preparation thereof.
2. of the Prior Art:
Dibutyltin fluoride (DBTF) is a known compound particularly useful for the manufacture of insulating glasses which reflect infrared radiation.
For this application ("hardcoating"), DBTF is deposited onto the glass in a layer of predetermined thickness. Accordingly, a product is required that is not heterogeneous, i.e., it must have a well defined grain size distribution of about 10 .mu.m and a highly specific platelet morphology. It should also be available in the form of a powder, which itself should not be adhesive.
Several processes are known to this art for the preparation of organotin fluorides and specifically DBTF. These processes entail reacting a fluorinating agent with a stannic substrate.
Exemplary such fluorinating agents include the alkali metal fluorides such as KF, ammonium fluoride, and aqueous or anhydrous hydrofluoric acid. Exemplary such stannic substrates include dibutyltin oxide, dibutyltin chloride and dibutyltin acetate.
The reaction may be carried out in an aqueous or methanol medium, for example in aqueous HF, or in anhydrous HF alone.
All of the prior art processes, however, in addition to their specific disadvantages, present one major common defect. Indeed, each produces a product having a highly variable morphology.
Accordingly, serious need exists in this art for organotin fluorides having a controlled morphology, in particular organotin fluoride in the form of platelets and having a restricted grain size distribution.